Apparatus and method for the direct casting of metal



E. B. HUDSON June 26, 1962 APPARATUS AND METHOD FOR THE DIRECT CASTING OF METAL 5 Sheets-Sheet 1 Filed May 6, 1957 INVENTOR.

5 Sheets-Sheet 2 ATTORNEYS- June 26, 1962 E. B. HUDSON APPARATUS AND METHOD FOR THE DIRECT CASTING OF METAL Filed May 6, 1957 um R.N, A WW. E a W 3 J, W 5% Y B w\\\ June 26, 1962 E. B. HUDSON 3,040,396

APPARATUS AND METHOD FOR THE DIRECT CASTING OF METAL Filed May 6, 1957 5 Sheets-Sheet I5 Bad I? il klll llll illl ly) lira-9.

I N VEN TOR. Eon IN .5. Haas 0M ATTORNEYS.

June 26, 1962 E. B. HUDSON 3,040,396

APPARATUS AND METHOD FOR THE DIRECT CASTING OF METAL Filed May 6, 1957 5 Sheets-Sheet 4 IN V EN TOR. Eon 11v .5. #006 04/,

A T TO R N E Y5- June 26, 1962 E. B. HUDSON 3,040,396

APPARATUS AND METHOD FOR THE DIRECT CASTING OF METAL Filed May 6, 1957 5 Sheets-Sheet 5 I N VEN TOR. tbwm .B- l/aasaM ATTORNEYS.

United States Patent 3,040,396 APPARATUS AND METHOD FUR "IFE DIRECT CASTING .UF METAL Edwin It. Hudson, Middletown, Ohio, assignor to Armco teel Corporation, Middletown, Ohio, a corporation of Ohio Filed May 6, 1957, 'Ser. No. 657,231 It) Claims. (Cl. 22-573) This invention relates to the direct or continuous casting of metals and more particularly to the casting of molten metal into bars having either a round crosssection or into a rectangular or other section which is not round or circular.

One of the principal causes of failure in the direct casting of metal is the friction between the work and the casting die. It is the present practice to apply lubrication on vertical casting machines by dripping oil on the die surface at atmospheric pressure. On some types of horizontal machines oil is supplied at atmospheric pressure to an oil chamber surrounding the die at the hot end of the machine and the oil is urged into the machine by a partial vacuum from the cold end. These expedients have not, however, materially reduced the friction difficulties between the cast bar or rod and the die, and consequently the mo ten metal still tends to stick to the die and the frozen skin on the work ruptures and breakouts occur.

One of the principal objects of this invention is the provision of means to materially reduce the friction between the die and the work and thereby remove the principal cause of failure in casting molten metal directly into a solidified bar or rod.

A further object of my invention is the provision of a lubricating system which provides calibrated lubrication of the die in proportion to the speed of travel of the work.

Still a further object of my invention is the provision of mechanical means effective to continually move the die, either axially in a vibratory manner, or in a rotary manner about the work, depending upon the type of stock being formed, thereby producing a sliding movement between the die surface and the surface of the stock to insure free axial movement of the stock.

Still a further object of my invention is the use of a lubricant oil containing pulverized glass in suspension.

The foregoing, together with other objects of my invention which will appear hereinafter or which will be apparent to the skilled worker in the art upon reading these specifications, I accomplish by those constructions and arrangements of parts and by those procedures of which I shall now describe certain exemplary embodiments.

Reference is now made to the accompanying drawings wherein:

FIGURE 1 is a plan view of a direct casting machine for rectangular stock; 7 v

FIGURE 2 is a side elevational View of the device of FIGURE 1. 7 I Y I 7 FIGURE 3 is an enlarged horizontal sectional View taken along the line 33 of FIGURE 2 with intermediate parts broken away.

FIGURE 4 is a side elevational View with parts in section of a casting die in accordance with my invention.

FIGURE 5 is an end elevational view of the casting die of FIGURE 4. i

FIGURE 6 is a fragmentary sectional view taken along the line 66 of FIGURE 3. 7

FIGURE 7 is a vertical sectional View taken along the line 7-7 of FIGURE 3.

FIGURE 8 is a vertical sectional view taken along the line 8--8 of FIGURE 4.

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FIGURE 9 is a diagrammatical view illustrating means to supply oil to the die in calibrated amounts.

FIGURE 10 is a vertical sectional View of an alterna- 'tive form of casting machine embodying a rotating die.

FIGURE ll is a fragmentary vertical sectional view of the die with the parts in exploded relationship.

FIGURE 12 is a vertical sectional view taken along the line 1212 of FIGURE 10.

FIGURE 13 is a fragmentary vertical sectional view taken along the line t1313 of FIGURE 10.

Briefly, in the practice of my invention, I provide the casting machine incorporating a system for forced lubrication under adjustable pressure and volume control. To accomplish this, the oil is supplied in metered quantities by a gear pump driven by the pinch rolls which drive the work. With this arrangement the quantity of oil supplied is in proportion to the speed of the work and the oil supply can be readily adjusted to suit operating conditions. The lubricating oil preferably contains pulverized glass in suspension which makes it possible to extrude a wider variety of metals.

Mechanical means are also provided to move the die with respect to the work to prevent adhesion. In one form of the invention wherein rectangular work, is. work of non-circular cross-section, is being handled, the casting die is caused to reciprocate axially at high speeds by means of vibrators, the axial vibration eifecting a sliding movement between the die and the work. Where the work is of round or circular cross-section, the die is mounted to rotate around the work to provide what may be deemed a compound sliding movement between the die surfaces and the surface of the cast rod, thereby again insuring free axial movement of the rod.

With the foregoing general considerations in mind, I shall'now proceed to give a detailed description of theseveral embodiments of my invention. Referring first to FIGURES l and 2 of the drawings, I have therein illustrated a casting machine 1 and a tundish 2 supported on a common base or bed '3. The casting machine com prises a central housing 4 terminating at the hot end ofthe machine in a hollow member 5 to which cooling water is supplied through a passageway 6 connected to a source of water under pressure. The housing has a centrally disposed longitudinal bore 7 (FIGURE 3) communicating at one end with the hollow member 5 and at the opposite or cold end with a second hollow member 8 having an exit passageway 9 through which the cooling'water is discharged. An elongated hollow die It is concentrically disposed within the bore '7 and sliclably supported at its ends by the sleeves I1 and 12 forming pa1ts of the hollow members 5 and 8, respectively. An annular passageway 13 is thus formed between the bore 7 and the outer surface of die It} through which the cooling water flows, the die being sealed at its ends to the sleeves 11 and 12 by means of suitable packing rings or the like 14. At the cold end of the machine, I prefer to interpose a separator 15 between the die and the member 8, the separator seating at its inner end against the housing 1 and held in place by means of a retaining nut =16 threaded on the end of the die.

At its hot end the projecting end of the die 10 slidably receives a nozzle 17 secured to a housing 18 mounted on the tundish 2. The nozzle 17 is spaced from the cylindrical inner wall of the die by a distance suflicient to provide a narrow passageway 19 for the passage of oil to the free end of the nozzle. Oil is supplied to the passageway 19 from chamber 20 opening through the die and fed by conduit 21 which, as will be explained more fully hereinafter, is connected to a source of supply from which lubricating oil is pumped in accordance with the speed of travel of the work. Nozzle 17 preferably has a metal body and a refractory lining 22. Conduits 23 extend longitudinally through the nozzle so that cooling water may be introduced through passageway and evacuated through passageway 26.

The die itself, as seen in FIGURES 4 and 5, will be preferably formed of copper and provided externally with longitudinally extending cooling fins 27 (best seen in FIG- URES 6, 7 and 8) to increase the rate of heat transfer from the molten metal to the cooling water. The inside surface of the die is preferably plated with Channelchromium in which the crystallite size of the chromium is controlled as the crystals form with electrodeposition. This method of plating produces channels which are about .001" deep and hence provides means to insure lubrication which is not possible with the smooth chromium plate conventionally employed in dies of this character. It will be understood that the die cavity 28' may be rectilinear or of such other configuration as desired, inclusive of a round or circular cross-section, although where round stock is being formed, I prefer to use the alternative apparatus to be hereinafter described.

It will be understood, of course, that molten metal will be extruded from the nozzle 17 into the die cavity 28 where it will be caused to solidify, thereby providing a continuous length of stock 29 which, as seen in FIGURES 1 and 2, is withdrawn from the die by means of pinch rolls 30 and 31 driven in accordance with the delivery speed of the stock.

In accordance with my invent-ion, a thin layer of oil will be extruded from the annular passageway 19 so as to form a lubricating film between the extruded metal and the walls of the die cavity. The oil is supplied in metered quantities under suitable pressure to prevent backflow of the molten metal before solidification occurs. To accomplish this, the oil is supplied by a gear pump driven by the pinch rolls which drive the stock. Thus, as seen in FIG- URE 9, the conduit 21 is connected to a gear pump 32, driven by an adjustable belt speed drive 33 in turn driven by gear 34 and pinion 35 mounted on pinch roll shaft 36 to which one or the other of the pinch rolls 30 or 31 is secured. Shaft 36 will be power driven from a suitable source of power which is not shown. A supply tank 37 will supply oil to the pump 32 for transmission through conduit 21 to the oil chamber 20. With this arrangement, the oil supply can be adjusted to suit the conditions of use but after adjustment will remain constant excepting for changes occasioned by variations in the feeding speed of the stock.

While conventional lubricating oils may be used, I prefer to use a lubricant oil containing pulverized glass in suspension. The use of glass or glass cloth has made it possible to extrude stainless steel, whereas without the inclusion of the glass only aluminum or magnesium could be extruded. The glass fibers will be pulverized to 300 mesh or finer and added to the oil in large quantities. A lubricant composed of 50% glass and 50% oil has been found highly satisfactory. Preferably, the pulverized glass will be used in as large a quantity as possible, using a lubricant which can be pumped with a gear pump. The primary purpose of the lubricant is to provide a means to pump the pulverized glass into the die. Under the high temperatures of casting, the oil will burn and the glass will melt to form the desired lubrication between the die and the work.

Referring again to FIGURES 1 and 2, the entire casting machine 1 is supported by electrical vibrators 38, 39, 40 and 4-1 which are mounted on springs 42, the springs in turn being supported by the machine bed 3. With this arrangement, the entire casting machine will be free to vibrate independently of the tundish 2 and the bed 3. The machine housing and die are vibrated in the direction of the longitudinal axis of the die which is free to vibrate relative to the nozzle 17. There is no axial vibration of the nozzle 17 or the tundish 2.

The tundish is supported on a bed section 43 having thus slides 44 along which the tundish can be moved away from the casting machine, thereby withdrawing the nozzle 17 from the hollow member 5 and die 10. This may be accomplished by means of a hand wheel 45 and screw 46 connected at one end to the tundish.

In the operation of the device, it is preferred to reciprocate the die housing axially at a frequency of 3600 cycles per minute at an amplitude of A3" to A. This may be readily accomplished by the use of Syntron vibrators which are commercially available. In an exemplary castoperation for the formation of a 6" x 6" section of rectangular bar stock, the stock maybe cast at a speed of 5 feet per minute, although casting speeds up to inches per minute are practical utilizing my casting machine and casting procedures. Preferably, the oil film between the stock and the walls of the die will have a thickness of .025", which means that for a 1 inch section of 6" x 6" stock, at least 0.6 cubic inch of oil must be supplied. The flow of oil should be equal to or faster than the casting speed so as to prevent backflow of the molten metal before solidification occurs. Consequently, in the exemplary embodiment given, the oil will be pumped at a rate of at least 536 cubic inches per minute. It will be readily apparent that the oil pump may be adjusted to obtain the desired rate of flow depending upon the dimensions of the stock and its feeding speed. Once adjusted, the rate of flow will be directly proportional to the feeding speed of the stock and, should the feeding speed be increased or decreased, the rate of flow of the oil will be increased or decreased proportionately.

Where stock having a round cross-section is to be formed, I have found it advantageous to effect a compound sliding movement between the stock and the die by rotating the die around the stock rather than setting up a vibratory movement of the die. Cylindrical stock produced in this manner will be of constant diameter and may be rolled on a mill to all other sizes required below the direct casting diameter. Since the basic construction of the rotary machine is the same as that of thevibratory machine, like reference numerals have been employed in the drawings for like parts wherever possible.

The principal difference between the two machines lies in the mounting of the central housing 4 which, as seen in FIGURE 10, is rotatably journaled in bearings 50 and 51 secured to the hollow members 5 and 8, respectively, by means of stud bolts 52. The end members 5 and 9 are fixedly secured to machine frame 53'. The housing is mounted for rotary movement relative to the end members.

As seen in FIGURE 11, the die 10a is adapted to slidably receive the nozzle 17, although in this instance the die may carry an annular flange '54 by means of which the die is fixedly secured to the central housing 4, as by means of stud bolts 55, thereby securing the die for rotation with the housing. The die will, of course, rotate relative to the nozzle 17. Rotation of the housing and die is obtained by means of a bevel gear 56 fixed to one end of the housing and driven by bevel pinion 57 formmg a part of the gear mechanism 58 which is driven by prime mover 59 mounted on the machine frame.

As in the case of the embodiment of FIGURES 1 through 9, the rotary die will be made of copper and plated with porous chromium on the stock contacting surfaces. However, in this embodiment of the invention, the external cooling fins are omitted. Where a higher heat transmission rate is desired, a silver die may be employed since such die has a K value of 1.04 as compared to the K value of a copper die which is 0.84. The use of a silver die results in a 24% increase in the heat transmission properties of the die. It will be understood that the molten metal will be supplied to the tundish 2 from which it will be injected into the die through the nozzle 17 which, as before, may be cooled. When the molten metal contacts the die solidification begins, forming a frozen metal skin against the die until the entire cross-section of the stock is solidified. Oil under pressure will be pumped into the die through the chamber 20 and, as before, the quantity of oil supplied will be in proportion to the speed of the work withdrawn from the die by the pinch rolls 31 and 32..

In the operation of the rotary device, the rotational surface speed of the die should not be less than the casting speed, ie the lineal speed of the stock being formed, although a higher rotational rate may be employed. in an exemplary commercial embodiment of the rotary device now in operation, a two inch diameter rod is being cast at 58 inches per minute with a die rotation of 9.25 r.p.m., the device being operated on a twenty-four hour, six day a week basis. In this operation the rotational speed of the die at the surface of the work is equal to the casting speed of the stock, although, as indicated, a higher rotational speed for the die may be employed. As in the case of the vibratory embodiment of the invention, the lubricant will be pumped along the walls of the die at a rate of flow at least equal to the lineal speed of the Work.

Thus, in accordance with my invention, friction reduction is accomplished by:

(l) The provision of forced lubrication under adjustable pressure and volume control.

(2) Mechanical movement of the die with respect to the stock by either:

(a) Vibratory movement of the die in the direction of the longitudinal axis of the die, or

(b) Rotary movement of the die about its long tudinal axis.

By means of the foregoing expedients I have found that the principal cause of failure in casting molten metal directly into a solidified rod or bar can be eliminated. Modifications may, of course, be made in my invention without departing from the spirit of it. Having thus described my invention in certain exemplary embodiments, what I desire to secure and protect by Letters Patent is:

1. In a method of direct casting molten ferrous metal wherein the molten metal is injected into one end of an elongated, open ended tubular die and solidified as it is continuously moved through said die, the steps of directly introducing a lubricant into the first named end of said die to form a film between the walls of said die and the surface of the molten metal, said lubricant being injected under continuous pressure in proportion to the speed of travel of the stock being formed, and rotating said die about its longitudinal axis relative to said stock at a rotational speed at the surface of the die which is at least equal to thelineal speed of travel of the stock being formed.

2. In a method of direct casting wherein molten metal is injected into one end of a horizontally disposed elongated open ended tubular die and solidified as it is continuously moved through said die, the step of introducing a lubricant directly into the first named end of the die to form a film between the walls of the die and the surface of the molten metal, said lubricant comprising pulverized glass in a liquid lubricating medium, said lubricant being injected under continuous pressure and at a rate of flow sufficient to cause said lubricant to flow lengthwise along the walls of said die at a speed at least equal to the lineal speed of travel of the stock being formed, whereby to prevent backflow of the molten metal before solidification thereof occurs.

3. The method claimed in claim 2 wherein said lubricant is composed of approximately equal proportions of lubricating oil and pulverized glass.

4. The method claimed in claim 3 wherein said pulverized glass is capable of passing a 300 mesh screen.

5. In a device for the direct casting of metal, a housing, a tubular open ended die mounted within said housing, said die being formed from copper and plated as to its inner surfaces with chromium in which the crystallite size of the chromium is of such character as to produce channels therein having a depth of substantially .001 inch, means for circulating a fluid coolant between said housing and said die to solidify molten metal passing through said die, means mounting said housing and said die for rotary movement about the longitudinal axis of said die and relative to the metal solidifying therein, means for rotating said housing and die, a set of driven pinch rolls positioned to engage the solidified stock as it emerges from said die, said pinch rolls being fixed against rotation with said housing and die and acting to withdraw the solidified stock from said die, means for continuously introducing oil under pressure directly into the leading end of said die, said last named means including a pump, and means for operating said pump in timed relation to said driven pinch rolls, whereby said lubricant will be introduced into said die in proportion to the speed of travel of the stock.

6. In a device for the direct casting of metal into solid bar stock, an elongated horizontally disposed housing, an elongated tubular open ended die mounted Within said housing, said tubular die being free from internal obstructions so that a solid bar may be cast therein, means for introducing molten metal into the leading end of said die, means for circulating a fluid coolant between said housing and said die to solidify the molten metal as it passes through said die, a passageway at the leading end of said die through which fluid lubricant is introduced into said die, a conduit connecting said passageway to a source of fluid lubricant, a driven pump connected to said conduit for supplying lubricant under pressure to the leading end of said die, driven pinch rolls positioned beyond the trailing end of said die to engage and Withdraw the solidified stock as it emerges from said die, means for driving said pinch rolls, and means operatively connecting said pinch roll drive means and said pump and acting to drive said pump in timed relation to said pinch rolls, thereby varying the quantity of lubricant introduced into said die in direct proportion to the speed at which the stock is withdrawn from said die.

7. The device claimed in claim 6 wherein including vibrator means operatively connected to said housing for effecting continuous vibration of said housing and die in the direction of the longitudinal axis of said die.

8. The device claimed in claim 6 wherein said housing and die are mounted for joint rotary movement about the longitudinal axis of said die, and wherein means are operatively connected to said housing for rotating said housing and die about the longitudinal axis of said die.

9. In a method of direct casting molten metal into solid barstock wherein the molten metal is injected into the leading end of an elongated open ended tubular die and solidified as it is continuously moved through the die and withdrawn from the trailing end thereof, the steps of continuously introducing a lubricant into the leading end of said die and forming a film of lubricant between the Wall of the die and the surface of the molten metal being cast, and driving means for positively forcing lubricant into said die in direct proportion to the speed of exit of the cast structure from the apparatus, whereby to maintain a substantially uniform and continuous film of lubricant between the bar stock being formed and the wall surfaces of the die irrespective of variations in the lineal speed at which the stock is withdrawn from said die.

10. The method claimed in claim 9 including the step of continuously vibrating said die during casting.

References Cited in the file of this patent UNITED STATES PATENTS Stravs et al. Dec. 13, 1904 (@ther references following page} 7 8 r 2,295,041 Iunghans Sept. 8, 1942 2,837,791 Tessmann June 10, 1958 2,376,518 Spence May 22, 1945 FQREIGN PATENTS 2,408,514 Hazelett Oct. 1; 1946 2423151 Miner July 1, 1947 768,991 Great Bntam Feb. 27, 1957 2,527,545 Goss Oct. 31, 1950 5 OTHER REFERENCES 1 2,699,609 Tarmanfi et 5, 1954 Metals Handbook, American Society for Metals, 2,702,419 Mattson F613. 2 1955 Cleveland, 1948, page 719, 2,775,008 Easton et a1. Dec. 25, 1956 Glass Lubricant in the Extrusion of Steel, J. Sejournet 2,803,215 Edgecombe et a1 Aug. 20, 1957 and J. Delcroix Lubrication Engineering v. 11, Novem- 2,825,947 Goss Mar. 11, 1958 10 bet-December 1955, pages 389-396. 

1. IN A METHOD OF DIRECT CASTING MOLTEN FERROUS METAL WHEREIN THE MOLTEN METAL IS INJECTED INTO ONE END OF AN ELONGATED, OPEN ENDED TUBULAR DIE AND SOLIDIFIED AS IT IS CONTINUOUSLY MOVED THROUGH SAID DIE, THE STEPS OF DIRECTLY INTRODUCING A LUBRICANT INTO THE FIRST NAMED END OF SAID DIE TO FORM A FILM BETWEEN THE WALLS OF SAID DIE AND THE SURFACE OF THE MOLTEN METAL, SAID LUBRICANT BEING INJECTED UNDER CONTINUOUS PRESSURE IN PROPORTION TO THE SPEED OF TRAVEL OF THE STOCK BEING FORMED, AND ROTATING SAID DIE ABOUT ITS LONGITUDINAL AXIS RELATIVE TO SAID STOCK AT A ROTATIONAL SPEED AT THE SURFACE OF THE DIE WHICH IS AT LEAST EQUAL TO THE LINEAL SPEED OF TRAVEL OF THE STOCK BEING FORMED. 